Rockwool LRB Home Rockwool LRB (Loose Rockwool Batt) Loose Rockwool Batt (LRB) is a flexible mineral-wool insulation spun from basalt fiber through a high-temperature melting process, then formed into loose batts. It is designed for easy installation and works well for filling irregularly shaped spaces such as wall or ceiling cavities where rigid insulation is […]